<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
  #main {
    width: 400px;
    height: 150px;
    border: 1px solid #c3c3c3;
    display: flex;
  }

  #main div {
    width: 70px;
    height: 70px;
  }

  /*!* Safari 6.1+ *!*/
  /*div#myRedDIV {*/
  /*  -webkit-order: 2;*/
  /*}*/

  /*div#myBlueDIV {*/
  /*  -webkit-order: 4;*/
  /*}*/

  /*div#myGreenDIV {*/
  /*  -webkit-order: 3;*/
  /*}*/

  /*div#myPinkDIV {*/
  /*  -webkit-order: 1;*/
  /*}*/

  /* Standard syntax */
  div#myRedDIV {
    order: 2;
  }

  div#myBlueDIV {
    order: 4;
  }

  div#myGreenDIV {
    order: 3;
  }

  div#myPinkDIV {
    order: 1;
  }
  </style>
</head>
<body>
<div id="main">
  <div style="background-color:coral;" id="myRedDIV">2</div>
  <div style="background-color:lightblue;" id="myBlueDIV">4</div>
  <div style="background-color:lightgreen;" id="myGreenDIV">3</div>
  <div style="background-color:pink;" id="myPinkDIV">1</div>
</div>
</body>
</html>